Obesity is a disorder of multiple etiologies, with an onset and development in human beings that has been recognized as having genetic, environmental, and behavioral factors. Obesity is a significant health problem in the developed world and is becoming an increasingly larger problem in the developing world. For example, in the American adult population, one out of three people is considered obese. Obesity is defined by the United States Centers for Disease Control and Prevention (CDC) as an excessively high amount of body fat or adipose tissue in relation to lean body mass and overweight as an increased body weight in relation to height, when compared to some standard of acceptable or desirable weight. The CDC alternatively defines overweight as a person with a body mass index (BMI) between 25.0 and 29.9 and obesity is defined as a BMI greater than or equal to 30.0. Obese and overweight mammals suffer from increased joint problems, increased rates of high blood pressure, and high cholesterol. Increased weight is also associated with heart disease, stroke and diabetes. In 1998, for example, consumers spent $33 billion in the United States for weight-loss products and services with very little success (Serdula, et al., Prevalence of Attempting Weight Loss and Strategies for Controlling Weight, JAMA 282:1353 1358, 1999). Thus, obesity and its associated complications continue to be a major problem throughout the worldwide health care system.
Excessive adipose tissue in the human body, resulting from either genetic or environmental factors, will cause a variety of additional symptoms associated with chronic disease states. These disease states include, but are not limited to, hyperlipidaemia, coronary atherosclerosis, severe carbohydrate intolerance, gout, gall bladder disease, degenerative arthritis, cancer, and infertility.
Currently there are no real cures or non-invasive treatments for obesity. Of the currently known techniques for treating obesity, the most prevalent are pharmacological attempts to suppress appetite or to inhibit intestinal absorption of nutrients. Pharmacological solutions to the problem of obesity generally take one of three different approaches:
1) Pharmacological approach to affect the brain;
2) Pharmacological approach to affect lipid absorption during meals; and
3) Pharmacological approach to affect fat cells per se.
A significant drawback to these approaches is that with the use of any drug to affect these mechanisms, there are a myriad of potential side effects, such as potential central nerves system (CNS) problems and problems with absorption of critical fat and fat-soluble soluble nutrients, that contribute to the early termination of such therapies. Available pharmacotherapies have included Sibutramine, Orlistat™, fenfluramine and dexfenfluramine. Fenfluramine and dexfenfluramine were withdrawn from the market in 1997 because of associated cardiac valvulopathy (Connolly, et al., Valvular Heart Disease Associated With Fenfluramine-Phentermine, New Engl J Med 337 581 588, 1997). Consequently, many health care professionals are reluctant to use pharmacotherapy in the management of obesity. Complimentary approaches to pharmacotherapy may therefore be of great interest to the public.
There are other moderately effective approaches for weight loss or treating obesity, such as behavioral modification, diets, and surgery. To date, the results of all of these approaches have been unsatisfactory, and usually only a moderate proportion of adipose reduction is achieved, but rarely maintained. Although behavioral modification and dietary restriction might be the most desirable methods for weight loss, long-term success of dietary regulation is low because of noncompliance. The loss of motivation to change behavioral and dietary habits necessary to consume less fat and fewer calories results in regaining weight.
Of surgical methods available, suction lipectomy, commonly known as liposuction, is the most common procedure for removing subcutaneous fat in the body. In general, the procedure involves the use of a special type of curette or cannula which is coupled to an external source of suction. An incision is made in the target area and the fatty tissue is essentially vacuumed from the patient's body. This procedure has its disadvantages, however, because the fat is relatively difficult to separate from the surrounding tissue. Such separation often causes excessive bleeding and damage to adjacent tissue or muscles. Other than causing collateral damage to surrounding muscle, blood vessels, skin, nerve, and subcutaneous tissues, liposuction can result in unattractive loose skin, postoperative hemorrhagic complications, pain, trauma, infection, and even death.
In addition to physical injuries associated with liposucion, it has been experimentally and clinically shown that the removal of large amounts of abdominal subcutaneous fat via liposuction does not appreciably alter the levels of circulating mediators of inflammation, that are almost certainly involved in the development of insulin resistance, Diabetes and coronary heart disease.
Adipose tissue is now documented as a significant endocrine organ that produces numerous bioactive proteins, including interleukin-6, tumor necrosis factor (alpha), and adiponectin. The production of adiponectin by adipose tissue can improve insulin sensitivity and inhibit vascular inflammation, while interleukin-6 and tumor necrosis factor (alpha) are known to cause insulin resistance, diabetes, atherosclerosis by damaging insulin signaling, increasing hepatic synthesis of C-reactive protein, and increasing systemic inflammation. As stated above, since it has been experimentally and clinically shown that the removal of large amounts of abdominal subcutaneous fat via liposuction does not appreciably alter the levels of circulating mediators of inflammation (markers of insulin resistance, diabetes and coronary heart diseas) there is a need in medical therapy to achieve a device and therapy that can augment naturally occurring lipolytic activity.
Weight-loss that is achieved by conventional obesity treatments (diet and exercise) decreases plasma concentrations of C-reactive protein, interleukin-6, and tumor necrosis factor-alpha and increases the concentration of adiponectin. In stark contrast, liposuction does not significantly change the plasma concentrations of any of these markers. Additionally, fat removal by liposuction has been shown to decrease plasma leptin concentration, which is a marker of adipose-tissue mass, which is not desirable as it has been implicated as a potent appetite suppressant.
Despite its undesirable side-effects, liposuction is still being used extensively. Various new methods have been devised to augment the procedure by taking advantage of the ultrasonic vibrations or laser energy to physically melt the fatty tissue so that it can be emulsified and aspirated through the liposuction probe. These ultrasonic probes have reduced the physical exertion required by the surgeon to remove fatty tissue, increased the speed of the operation and reduced collateral damage created at the incision point. One problem with these probes, however, is excess heat generation at the distal tip of the probe, which can readily be in excess of the temperature required for melting the fatty tissue. This excess heat often results in burning of tissue, damaging muscles or blood vessels, and even penetrating membranes such as the skin or the peritoneum that covers most of the intra-abdominal organs.
Among the methods that exploit laser energy to remove unwanted fat, U.S. Pat. Nos. 6,605,080 and 7,060,061 issued to Altshuler, et al. represent an alternative approach in which laser energy is externally applied to the skin to heat and melt fat tissues in epidermis and subcutaneous layers below. These patents disclose the use of near infrared radiation to heat-liquefy fat cells, after which the lipid pool is removed from the subcutaneous area by aspiration. Because of the considerable heat generation that results from the techniques, e.g., up to 70° C., at or in the fat tissue, a special cooling mechanism must be in place to prevent potential temporary skin damage or permanent scarring, with permanent scarring occurring primarily in the dermis. These methods present other limitations and potential adverse thermal effects on tissue above the lipid-rich tissue under treatment, including blistering, peeling, and depigmentation.
Therefore, there remains a need for an improved non-invasive method and device for reducing fat and alleviating obesity without excessive heat deposition at the site of treatment; a technique which does not suffer from the noted limitations of the background art; and a method and device that can be utilized by the general public with convenience and ease.